Simplify flattening to just write enough to call the factory

src/effects/SkComposeImageFilter.cpp

Index: src/effects/SkComposeImageFilter.cpp
diff --git a/src/effects/SkComposeImageFilter.cpp b/src/effects/SkComposeImageFilter.cpp
index 645d63372a0ccd475c72a87e7613edb1ecaede18..68dc7467d0b5e9d16ebb789dd503e88b9a010ea3 100644
--- a/src/effects/SkComposeImageFilter.cpp
+++ b/src/effects/SkComposeImageFilter.cpp
@@ -53,6 +53,23 @@ bool SkComposeImageFilter::onFilterBounds(const SkIRect& src,
            outer->filterBounds(tmp, ctm, dst);
 }
 
+SkFlattenable* SkComposeImageFilter::CreateProc(SkReadBuffer& buffer) {
+    Common common;
+    if (!common.unflatten(buffer)) {
+        return NULL;
+    }
+    switch (common.inputCount()) {
+        case 1:
+            return SkRef(common.inputs()[0]);
+        case 2:
+            return SkComposeImageFilter::Create(common.inputs()[0], common.inputs()[1]);
+        default:
+            return NULL;
+    }
+}
+
+#ifdef SK_SUPPORT_LEGACY_DEEPFLATTENING
 SkComposeImageFilter::SkComposeImageFilter(SkReadBuffer& buffer)
   : INHERITED(2, buffer) {
 }
+#endif